In Parshas Matos, the tribes of Reuven, Gad, and half of Menashe approach Moshe with the following proposal, "The land that Hashem smote before the assembly of Israel, it is a land of livestock, and your servants have livestock. If we found favor in your eyes, let this land be given to your servants as a heritage, do not bring us across the Jordan" (Bamidbar 32:4-5).
In responding to Moshe, the two and a half tribes said that they would build pens for their livestock and cities for their children. Rashi (32:16) cites the Medrash Tanchuma that Moshe criticized them for having misplaced priorities, as is evidenced by their placing the livestock before their children - their children should have taken precedence over their business ventures. Yet, our rabbis in the Medrash Hagadol teach a significant positive character trait of the tribe of Reuven. They were concerned that due to their large quantity of cattle, and perhaps insufficient grazing land in the Land of Israel, they would come to trespass and steal pasture lands from others. Rather than violate the biblical prohibition of theft, they preferred to remain on the other side of the Jordan River.
The rabbis further note (Beraishis Rabba 72:2) that this great sensitivity towards theft came from the founder of the tribe of Reuven. In Braishis (30:14) we are taught that Reuven brought dudaim (mandrakes) to his mother Leah. The Medrash (ibid) notes in praise of Reuven that he was careful not to take any flowers or grain from private property, only from that which was open to the public and ownerless. The medrash continues and cites the passuk (Mishlei 22:6), "Educate the child in his youth, for even in his years of maturity he will not deviate there from." The rabbis attribute the sensitivity of bnei Reuven to their ancestor Reuven. We thus see that a great deal more than DNA is transmitted to our children and grandchildren. While each person and generation has their own free will, they are given a greater propensity towards either a virtuous or other direction from their parents and indeed ancestors.
While this aspect of the value system of Bnei Reuven was most praiseworthy, a careful analysis of the text, as presented by Sforono, points to another deficiency on the part of Bnei Reuven. Moshe (32:22) cites the condition of their acquiring the land in Ever HaYarden that it will become theirs after they successfully fulfill their mission of helping the other shevatim conquer the Land of Israel. They say no, and insist "We shall cross over to the Land of Canaan, and our land shall be ours immediately, and moreover we will stay not only for the years of conquest but also for the years of settlement as well" (32:34). Moshe, explains Sforno, (32:28) reluctantly acquiesces for the sake of peace and harmony.
Rav Shalom Shapera zt"l notes in his Hamaor ShebaTorah that this exchange between Moshe and Bnei Reuven is a further indication of Bnei Reuven's skewed priorities. Their primary concern for their land and business, even if conducted honestly, is not to supersede their responsibilities to their children. Bnei Reuven transmitted skewed priorities to their children, and it is no coincidence that the two and a half tribes were exiled before the other ten tribes by Sancherev (as found in Divrei Hayamim I:5): "She weeps bitterly in the night, and her tear is on her cheek" (Eicha 1:2). The Nesivos in his commentary on Eicha understands this to mean that the sin of neglect and disdain for Eretz Yisroel which was at the root of the sin of the meraglim on that very first Tisha B'av is still present in our midst. As Bnei Reuven favored another land over the Land of Israel, in order to have an easier more affluent livelihood, too many families reject aliyah and a higher living standard for fear of a significant decline in their standard of living.
Often they are consciously or subconsciously emulating Bnei Reuven by choosing materialism over a better environment for their children. While it is understandable that the post-war (WWI and WWII) immigrants to America, who had nothing, wanted a better and easier life for their children, unfortunately, while they proudly extolled the virtues of this land, they neglected to incorporate a love for our land.
Tisha B'av summons us not only to recollect and mourn the past, but to reevaluate the values we are currently transmitting to our children.